This invention relates generally to gas turbine engines and more particularly to fuel injectors for supplying fuel to the combustor of such engines.
A gas turbine engine includes a compressor that provides pressurized air to a combustor wherein the air is mixed with fuel and ignited for generating hot combustion gases. These gases flow downstream to one or more turbines that extract energy therefrom to power the compressor and provide useful work such as powering an aircraft in flight. In combustors used with aircraft engines, the fuel is typically supplied to the combustor through a plurality of fuel injectors positioned at one end of the combustion zone, and air is supplied through a surrounding assembly, known as a swirler, which imparts a swirling motion to the air so as to cause the air and fuel to be thoroughly mixed.
Conventional fuel injectors typically include an inlet stem that is mounted to the combustor casing and connected at one end to a fuel manifold. The other end of the inlet stem is connected to a fuel tube that carries the fuel to a fuel tip disposed in the swirler. A fuel filter is located in the inlet stem to remove any contaminants from the fuel stream prior to its introduction to the combustor. Because they are exposed to a relatively high temperature gas stream, fuel injectors are typically provided with some form of thermal protection to prevent overheating of the fuel as it passes through the fuel injector. Excessive heating of the fuel can lead to coke formation, which will cause the fuel injector to become clogged.
In an aircraft engine, a fuel leak could result in a fire and/or loss of power that would jeopardize the safety of the aircraft flight. Thus, it is desirable that the fuel delivery system be resistant to leaks or other failures. It is also desirable to use a one piece fuel manifold because of its relatively low cost. It has thus been proposed to use a double seal fitting to connect the inlet stem to the fuel manifold so that the fuel delivery system meets commercial fire safety standards. A double seal fitting is a known type of fitting that includes locking features for preventing separation of the inlet stem and the fuel manifold due to causes such as vibrations or the like.
However, use of a double seal fitting with a one piece manifold requires that the fuel filter be located further inside the inlet stem than is the case with other types of connections. Prior attempts to configure the inlet stem to accommodate the repositioned fuel filter have encountered problems with the manufacture of the inlet stems and the thermal protection of the fuel passing therethrough. Accordingly, there is a need for a fuel injector that can accommodate a double seal fitting while remaining easy to manufacture and providing adequate thermal protection.
The above-mentioned need is met by the present invention, which provides a fuel injector having an inlet stem with a bore formed therein and an insert disposed in the bore. The insert has a cavity formed therein for receiving a fuel filter.
The present invention and its advantages over the prior art will become apparent upon reading the following detailed description and the appended claims with reference to the accompanying drawings.